2. Extract the zip flle and upload PIE.htc to any web reachable directory.

Ex.:

public_html/assets/PIE.htc

3. Add position: relative; style to all those selectors for which you would like to use CSS3 PIE. You will of course be specifying border-radius/box-shadow etc. properties (which are supported by CSS3 PIE).

4. Check child theme directory using a FTP client or cPanel file manager. If single-<cpt>.php has not been automatically created, copy/upload single.php from parent Builder into the child theme and rename it as single-<cpt>.php.